The present invention relates generally to booms and more specifically to multi-section booms which are telescoped with respect to each other to vary the effective length of the boom.
The use of booms for handling various types of materials has been common practice for many years. Usually these booms are supported on some type of support structure or turntable which in turn is supported on a mobile frame so that the boom can be raised and lowered with respect to the turntable and the turntable can be rotated 360 degrees with respect to the support structure to increase the versatility thereof.
To further increase the versatility of the unit, the booms are formed in multiple sections which are telescoped within each other and can be extended and retracted to vary the effective length thereof. For example, presently there are several types of cranes that have a boom formed with three or more sections which are extended and retracted with respect to each other through suitable power means, such as fluid rams.
In the formation of booms of this type, it has been customary to form the respective boom sections from metal plates that are welded to each other and reinforced at appropriate locations to provide sufficient strength to support a load on the outer end thereof. It will be appreciated that this presents many problems in that a boom may have an overall length, with a jib assembly attached thereto, to extend more than 100 feet from the turntable or support.